Astronomer discovers star HD 10180 has more planets than the Sun

An astronomer has discovered that a star named HD 10180, close to our Sun in mass, temperature, brightness and chemical composition has more planets than the Sun. This is the first time scientists have discovered a star with more planets than the Sun.

Astronomer Mikko Tuomi at the University of Hertfordshire, discovered that the planetary system of HD 10180 may have nine planets. This makes the star's system the largest planetary system known to astronomers. Our solar system has only eight planets, down from nine after astronomers downgraded Pluto from a planet to a "protoplanet."

Discover Magazine reports the observations detected six Doppler shift signals indicating six planets, five Neptune-sized planets with masses ranging from 12-25 times the Earth. The sixth planet detected was 65 times the mass of our planet Earth, making it more like Saturn than Neptune. The seventh planet could not be ascertained.

The new analysis of data, using new statistical methods, confirmed a seventh planet in the system, and discovered two additional planets, bringing the total number of planets to nine. The three new planets have masses 1.3, 1.9 and 5.1 times that of the Earth and orbit the star with periods of 1.2,10, 68 days respectively. According to Discover Magazine, analysis showed the orbits of the planets are stable.

The first two planets in the alien system are in the Earth-mass range and are termed "super Earths." They are much closer to HD 10180 than the Earth is to the Sun.The first planet is 3 million km from the star and the second about 14 million km. This makes them very hot planets, too hot to support life.

Popular Science reports Tuomi thinks his analysis confirms existence of the seventh planet, but more evidence is required to confirm details of the other two planets.

Tuomi's discovery is significant because most planetary systems discovered so far have four planets or fewer. Even at seven planets confirmed, the planetary system of HD 10180 is unusual.